Protective device for unipolar machines.



No. 890,697. PATENTED JUNE 16, 1908. J. B. NOEGGERATH.

PROTECTIVE DEVICE FOR UNIPOLAR MACHINES.

APPLICATION FILED 00T.4.1905.

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J; E. NOEGGERATH.

PROTECTIVE IGE FOR UNIPOLAR MACHINES.

A ATION FILE-D 0014,1905.

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,TocZl whom it may concezirt: f 14- I Be it known that I, Jex'on E; Nonsens- I .4L'1'H, a'.citizen of the United States, residing h nec-tad State-of New new and useful Improvements in Protective Devices for Unipolar Machines, of: which the following is a specification. I

J M invention relates to dynamo-electric mac "nes of the unipolar type, and its object county. 'of Schenectady,

' into. provide means for protecting such macircuits, since such protection would neceschines a ainst accidental internal short-cir: cui ts,-' at is, against short circuits of individual armature conductors. In -coi1- wound d amo-electric it is not practicab e to guard against internal shortsitate the insertion of protective devices between the several turns ofthe coils of the machine. In unipolar machines, however, the several rotating armature conductors are not connected directly to each other, but the connection between them is formed by external stationary conductors extending from the brush or other collecting device at one end of one armature conductor to a similar brush at the opposite end of a second conductor. Consequently, in such a machine it is possible 1 to insert protective devices in these crossconnections, and such devices, if responsive to an abnormal flow of current, may be utilized to protect the machine against shortcircuits of individual conductors.

My invention consists in a'novel form of protective device actuated by the flux surrounding the cross-connecting conductors. By using this form of device I render it unnecessary to insert a coil in the cross-connec- 1 structure whichis provided with magnetizing field coils f. A represents the rotatable armature carrying a plurality of armature conductors a, which are shown held in place at the periphery of the armature by a steel ring or band a. Each armature conductor is connected at its opposite end to collector 'Dn vrcn Ion umromn xecnmns.

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the collector rings serve 'to lead off the current generated i i-the several armature conductorsl The brushes at opposite ends of the machineare cross-connected by stationary conductors b, which are arranged to place the several armature conductors in series. B- represents a rheostat or variable resistance in the field circuit. 0 e represent relays or protective devices in the crossconnections, which, when abnormal current flows in any one of the crossconnections, due to the shortcircuiting of an armature conductor, will close a circuit through a suitable source of current Gland through the trippin coils I i'ings Stationary brushes B bearing on and It of the'circuit-breakers II and f which .are placed in the main armature circuit and in the field circuit respectively. By the opening of the field circuit the machine is demagnetized, and in this manner protected against overheating due to the short-circuited armature conductor. The cross-connections b are usually of large size so that the insertion of coils directly in them,'as shown diagrammatically in Fig. 1, is inconvenient in practice. vice of the type shown in ig. 2, which ma be placed around a straight conductor an which is actuated by the flux surrounding the conductor.

In Fi 2, I represents a magnetic circuit in the orm of a loop surrounding one or Consequently, I refer to use a de-' more conductors b and comprising a mov- I able portion 1' which is normally held by a compression spring J in such a position as to form an air-gap in the magnetic circuit.

The spring J is proportioned to resist the pull on the member 't exerted by the normal ux surrounding the conductor 1), but if the conductor 6 should be short-circuited, the increase of flux due to the short-circuit current carried by member '2', into engagement with stationary contact K. A circuit is thus closed which may be used to open the field or armature circuit or both in the manner shown in Fig. 1.

In Fig. 3 I have shown atype of protective.

device ,which, like that of Fig. 2, utilizes the flux surrounding a straight conductor, but

which responds toa change in flux of a pre determined amount instead of to a constant flux of a predetermined strength. It comprises a magnetic loop I surrounding one or more conductors b and carrying a coil L. The loop I and coil L form the magnetic core and the secondary respectively of a transformer of which the conductor 1) forms the primary. Ordinary fluctuations in current in conductor if induce voltages in coil L in sullicientto actuate the device, such as the relay or tripmagnet M, supplied from the (soil, but if a short-circuit should occur, the rush of current would produce a great and rapid increase in the flux around conductor 1) and this would induce a voltage in coil L of slullicient magnitude to actuate the tripping evice.

Other arrangements of the protective devices may be employed as desired, and con-.. sequently I do not Wish to limit myself to the particular construction and arrangement of parts here shown, but aim in the a )pended claims to cover all modifications which are within the scope of my invention.

What I claim as new and desire to secure" by Letters Patent of the United States, is,

1. In a unipolar dynamo-electric machine, a revolving armature carrying a plurality of conductors, collector rings connected to opby said devices posite ends of said conductors, brushes bearing on said collector rings, conductors crossconnecting the brushes at opposite ends of the armature conductors, protective devices controlled by the flux surrounding said crossconnecting conductors, and means controlled for opening a circuit of the machine. p f

2. In a unipolar dynamo-electric machine, a revolving armature carrying a plurality of conductors,'collector ringsconnected to opposite ends of said conductors,- brushes bearmg on'said collector rings, conductors crossconnecting the brushes at opposite ends of the armature conductors, protective devices comprising portions surrounding said cross-v connecting conductors and responsiveto the flux surrounding said conductors, and means controlledby said devices for opening a circuit of the machine.

. In witness whereof, I'have hereunto set my hand this second day of October, 1.905.

JAKOB E. NOEGGERATH Witnesses:

BENJAMIN B. HULL, MARGARET E. WooLLEY. 

